Starting device for mercury arc rectifiers



Nov. 1, 1932.

M. URBINATI STARTING DEVICE FOR MERCURY ARC RECTIFIERS Filed 001:. 25, 1930 Patented Nov. 1, 1932 MARIO URBINATI, OF HOME, ITALY STARTING DEVICE FOR MERCURY ARC BEGTIFIERS Application filed October 25, 1930, Serial No. 491,098, and in Italy November 5, 1929.

As is well known, in mercury vapour rectifiers the mercury is usually contained in a cup, which may be variously shaped, and which is placed either in the lower part of the container or above it, the ends of the J anodes protruding above the surface of the mercury at a certain dlstance therefrom, the are being formed between the surface of the mercury and the anodes. At this point, the circuit is consequently interrupted and in order to induce the are to be formed at the start, the cup is usually shaken either by hand or by means of an electromagnet, so that the movement of the liquid mass caused by the shaking will produce splashes which facilitate the formation of the are, which, once formed, is maintained by the presence of the mercury vapour produced.

It is well known that a rotating magnetic field obtained by alternating polyphase currents is capable of imparting a rotating movement to a cylinder consisting of a conducting material and included in said field, and this principle has also been applied for causing the rotation of the mercury mass in mercury vapor reetifiers.

By the device being arranged in a 0011 venient manner, some of the liquid splashes produced by the above rotation may reach the anodes, or at least approach them near enough. to form the are, after which the. action of the rotating field may be stopped.

Serious inconveniences are, however, experienced when the mercury container with its electromagnetic ring for causing the rotation of the mercury is embodied into the rectifier, on account of the large amount of heat which is produced by the voltaic are during its op eration. My invention has for its object to eliminate this inconvenience by giving to the bulb a cylindrical shape and placing the cup,

surrounded by the electro-magnetie ring, outside the rectifier so that the air can freely circulate all around the bulb, thus preventing the undue heating of the apparatus.

The figure on the drawing shows an embodiment of the invention.

In this figure the cup 0 containing the mercury subjected to the action of the rotating field, is disposed outside the container h and forms a separate container which however communicates with the container h by the tubes -u and o. The mercury expelled by the upper tube while it is under the action of the rotating field. In this case the ring 2' is arranged around the cup -c-. It is evident that other arrangements may be adapted in addition to those described above without departing from the fundamental principle of the invention. Also, it is to be noted that the action of the rotating field may be intensified by placing in the cup 0, together with the mercury, an iron core (not shown) which may either be fixed or may rotate so as to increase the agitation of the mercury.

I claim:

Device for producing the formation of the are in mercury vapour rectifiers, comprising in combination a rectifier having a mercury cup at its bottom part, a cylindrical container filled with mercury and disposed externally of and at the same level as the bottom of said rectifier, a lower tube connecting the bottom of said rectifier with the bottom of said container, the mercury circulating from the for- Iner to the latter through said tube, a polyphase winding surrounding said container and arranged to produce a rotating magnetic field around said container, an upper tube connecting the top of said container with said rectifier, delivering the mercury therein at a level higher than the normal level of the mercury, two poles of an electric circuit, the first being inserted into said rectifier below and in correspondence to the delivery therein of said upper tube, and the other contacting with the mercury contained in said rectifier, the action of said polyphase winding surrounding said container causing the mercury therein to revolve and to raise its level along its sides due to the centrifugal action. developed thereby and. to escape through said upper tube into said rectifier, meeting; during its fall therein the pole of the electric circuit inserted below the delivery of said upper tube and falling on to the mercury in said rectifier thus establishing electrical contact between the said two poles of the electric circuit.

In testimony whereof I have afiixed my signature, at Rome this 14th day of October 1930.

MARIO URBINATI. 

